Tenemos la indeterminación de tipo
0/0,
tal que el límite para el numerador es
$$\lim_{x \to 0^+} \log{\left(\tan{\left(x + \frac{\pi}{4} \right)} \right)} = 0$$
y el límite para el denominador es
$$\lim_{x \to 0^+} \frac{1}{\cot{\left(\pi x \right)}} = 0$$
Vamos a probar las derivadas del numerador y denominador hasta eliminar la indeterminación.
$$\lim_{x \to 0^+}\left(\log{\left(\tan{\left(x + \frac{\pi}{4} \right)} \right)} \cot{\left(\pi x \right)}\right)$$
=
Introducimos una pequeña modificación de la función bajo el signo del límite
$$\lim_{x \to 0^+}\left(\log{\left(\tan{\left(\frac{4 x + \pi}{4} \right)} \right)} \cot{\left(\pi x \right)}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \log{\left(\tan{\left(x + \frac{\pi}{4} \right)} \right)}}{\frac{d}{d x} \frac{1}{\cot{\left(\pi x \right)}}}\right)$$
=
$$\lim_{x \to 0^+}\left(- \frac{\left(\tan^{2}{\left(x + \frac{\pi}{4} \right)} + 1\right) \cot^{2}{\left(\pi x \right)}}{\pi \left(- \cot^{2}{\left(\pi x \right)} - 1\right) \tan{\left(x + \frac{\pi}{4} \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(- \frac{2 \cot^{2}{\left(\pi x \right)}}{\pi \left(- \cot^{2}{\left(\pi x \right)} - 1\right)}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \frac{1}{- \cot^{2}{\left(\pi x \right)} - 1}}{\frac{d}{d x} \left(- \frac{\pi}{2 \cot^{2}{\left(\pi x \right)}}\right)}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{2 \cot^{4}{\left(\pi x \right)}}{\pi \left(\cot^{4}{\left(\pi x \right)} + 2 \cot^{2}{\left(\pi x \right)} + 1\right)}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \frac{1}{\cot^{4}{\left(\pi x \right)} + 2 \cot^{2}{\left(\pi x \right)} + 1}}{\frac{d}{d x} \frac{\pi}{2 \cot^{4}{\left(\pi x \right)}}}\right)$$
=
$$\lim_{x \to 0^+}\left(- \frac{\left(- 4 \pi \left(- \cot^{2}{\left(\pi x \right)} - 1\right) \cot^{3}{\left(\pi x \right)} - 4 \pi \left(- \cot^{2}{\left(\pi x \right)} - 1\right) \cot{\left(\pi x \right)}\right) \cot^{5}{\left(\pi x \right)}}{2 \pi^{2} \left(- \cot^{2}{\left(\pi x \right)} - 1\right) \left(\cot^{4}{\left(\pi x \right)} + 2 \cot^{2}{\left(\pi x \right)} + 1\right)^{2}}\right)$$
=
$$\lim_{x \to 0^+}\left(- \frac{\left(- 4 \pi \left(- \cot^{2}{\left(\pi x \right)} - 1\right) \cot^{3}{\left(\pi x \right)} - 4 \pi \left(- \cot^{2}{\left(\pi x \right)} - 1\right) \cot{\left(\pi x \right)}\right) \cot^{5}{\left(\pi x \right)}}{2 \pi^{2} \left(- \cot^{2}{\left(\pi x \right)} - 1\right) \left(\cot^{4}{\left(\pi x \right)} + 2 \cot^{2}{\left(\pi x \right)} + 1\right)^{2}}\right)$$
=
$$\frac{2}{\pi}$$
Como puedes ver, hemos aplicado el método de l'Hopital (utilizando la derivada del numerador y denominador) 3 vez (veces)